physics LE

Electric current

It flows through light bulbs

Electric circuit

It contains charges in motion

Circuits

Are the heart of modern devices such as computer, televisions, and industrial power systems.

Current

It is any motion of charge from one region to another.

I = dQ/ dt

Current is defined as: (formula)

Electric field

It causes charges to flow in a conductor.

Randomly

Path of electron without electric field; the electrons moves ___

Net displacement

Path of electron without electric field electric field, the motion of the electrons is mostly random, the electric field results in a ______ along the wire

Negative

Electron has a _____ charge.

Opposite

An electron has a negative charge, so the force on it due to the electric field is in the direction ____ to electric field.

I

What is the symbol for current?

E

What is the symbol for electric field?

q

What is the symbol for charge?

F

What is the symbol for steady force?

Current

Can be produced by positive or negative charge flow.

Conventional current

It is treated as a flow of positive charges, regardless of whether the free charges in the conductor are positive, negative or both.

Electrons

The moving charges in metals are ____

Vd

What is the symbol for drift velocity?

Current

In metallic conductors, the moving charges are electrons, but the ___ still points in the direction positive charges would flow.

n

What is the symbol for the number of particles?

dt

What is the symbol for time interval?

A

What is the symbol for area?

J

What is the symbol for current density?

J = I/A

What is the formula in finding the current density?

A = pie d²/4

What is the formula in finding the area?

Vd = J/n|q|

What id the formula in finding the drift speed?

Resistivity

Is the ratio of the electric field in the material to the current density it causes.

P = E/J

What is the formula of resistivity?

Conductivity

Is the reciprocal of resistivity.

Temperature

Resistivity depends on ____

Increases

In metals, resistivity ____ with increasing temperature.

Metals

Which form will the resistivity increase with increasing temperature?

Decreases

In semiconductors, resistivity ____ with increasing temperatures.

Semiconductors

What form will resistivity decrease with increasing temperature?

Superconductors

What form in which at temperatures below Tc, the resistivity is zero.

Zero

In superconductor, the resistivity is ____ at temperatures below Tc.